No evidence for reduced Simon cost in elderly bilinguals and bidialectals.

Journal of Cognitive Psychology, 2014 V\ Routledge

Vol. 26, No. 6, 640-648, http://dx.doi.org/10.1080/20445911.2014.929580 I > W^o^a^

No evidence for reduced Simon cost in elderly bilinguals

and bidialectals

Neil W. Kirk, Linda Fiala, Kenneth C. Scott-Brown, and Vera Kempe

Division of Psychology, Abertay University, Bell Street, Dundee DDI 1HG, UK

We explored whether a bilingual advantage in executive control is associated with differences in cultural
and ethnic background associated with the bilinguals' immigrant status, and whether dialect use in
monolinguals can also incur such an advantage. Performance on the Simon task in older non-immigrant
(Gaelic-English) and immigrant (Bengali, Gujarati, Hindi, Malay, Punjabi, Urdu-English) bilinguals was
compared with three groups of older monolingual English speakers, who were either monodialectal users
of the same English variety as the bilinguals or were bidialectal users of a local variety of Scots. Results
showed no group differences in overall reaction times as well as in the Simon effect thus providing no
evidence that an executive control advantage is related to differences in cultural and ethnic background
as was found for immigrant compared to non-immigrant bilinguals, nor that executive control may be
improved by use of dialect. We suggest the role of interactional contexts and bilingual literacy as
potential explanations for inconsistent findings of a bilingual advantage in executive control.

Keywords: Bidialectism; Bilingualism; Inhibitory control; Simon task.

Regular use of two or more languages requires
individuals to inhibit one language when using the
other, to select the appropriate linguistic setting
and individual words in the target language (Green,
1998; Hilchey & Klein, 2011). Habitual inhibition
of one language in bilinguals is assumed to lead to
transfer of improved executive control to non-
linguistic domains. This bilingual advantage,
demonstrated in a number of studies (for a review
see Bialystok, Craik, Green, & Gollan, 2009),
appears to be most pronounced in participants in
whom cognitive processes do not operate at peak
speed such as young children and older adults

(Bialystok, Martin, & Viswanathan, 2005). In particu-
lar, in older bilinguals, lifelong frequent use of two
languages may provide the practice needed to
improve executive functioning, which may help to
maintain cognitive flexibility later in life (Bialystok,
Craik, Klein, & Viswanathan, 2004).

Because random assignment is not possible in
quasi-experimental studies comparing bilinguals
with monolinguals, there remains the possibility
that bilingualism covaries with other factors that
can also affect executive functioning (Hilchey &
Klein, 2011), such as socio-economic status (SES;
Morton & Harper, 2007) and immigrant status,

Correspondence should be addressed to Vera Kempe, Division of Psychology, Abertay University, Bell Street, Dundee DDI
1HG, UK. E-mail: v.kempe@abertay.ac.uk

Some of the findings were reported at the 35th Annual Conference of the Cognitive Science Society. Parts of this research were
sponsored by a Carnegie Trust for the Universities of Scotland Travel Grant to Neil Kirk and by Leverhulme Trust Research Project
Grant [grant number RPG-375] to Vera Kempe.

The conditions of funding set by the Carnegie Trust for the Universities of Scotland and the Leverhulme Trust do in no way bias
or prejudice the outcomes of the funded research so the authors declare no conflict of interest.

© 2014 The Author(s). Published by Taylor & Francis.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.
org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited. The moral rights of the named author(s) have been asserted.

NO REDUCED SIMON COST IN ELDERLY BILINGUALS

641

which is associated with differences in cultural and
ethnic background. Even when bilinguals and
monolinguals are matched in SES, it is often
impossible to match them also in ethnic and
cultural background. Consider the studies that
examine older participants: In Bialystok et al.
(2004), the monolinguals resided in North
America whereas the majority of bilinguals
resided in India. Thus, although the bilinguals
were non-immigrants in their country of residence,
they clearly differed in cultural and ethnic back-
ground from the monolinguals. In Bialystok,
Craik, and Luk (2008), 20 out of 24 bilinguals
were immigrants from ethnical and cultural back-
grounds who had arrived in North America as
children or adolescents. Salvatierra and Rosselh
(2010) and Schroeder and Marian (2012) do not
explicitly report immigrant status, yet the ages of
English acquisition of their bilinguals suggest that
they too were predominantly first-generation immi-
grants differing in ethnic and cultural background
from the monolinguals. Thus, the specific bilingual
populations studied so far make it difficult to disen-
tangle bilingualism from other potential factors that
may be linked to differences in executive functioning.

An association of ethnic and cultural back-
ground with executive functioning (Sabbagh, Xu,
Carlson, Moses, & Lee, 2006) can be attributed to
culture-specific parenting attitudes or educational
and leisure practices which promote exposure to
activities that require executive control, such as
musical training (Bialystok, 2011), playing of video
games (Green & Bavelier, 2003) and other, as of
yet unstudied pursuits. Moreover, genetic effects
may also contribute to ethnic differences in exec-
utive functioning. For example, population-genetic
studies show that the prevalence of the 7-repeat
allele of the dopamine receptor gene (DRD4) is
markedly lower in East and South-East Asia
compared to North America (Chang, Kidd, Livak,
Pakstis, & Kidd, 1996). This allele has been
associated with attention-deficit hyperactivity dis-
order (ADHD; Faraone, Doyle, Mick, & Bieder-
man, 2001), which, in turn, often manifests itself in
poor executive functioning (Schachar, Tannock,
Marriott, & Logan, 1995). To examine these
potentially confounding effects, the present study
aimed to compare executive control in older
immigrant and non-immigrant bilinguals. The
immigrant bilinguals were speakers of English
and a language spoken in Asia and differed
in ethnic and cultural background from the
monolinguals. The non-immigrant bilinguals were
British speakers of Gaelic, an indigenous Celtic

minority language used by about 58,000 indivi-
duals residing mainly in the West of Scotland.
Since Gaelic-medium schooling was abolished in
1872 and reintroduced only in 2006, these partici-
pants had acquired Gaelic in early childhood
before being introduced to English in school and
tended to use Gaelic in the home and in the local
bilingual community. Crucially, in terms of ethnic
background, cultural attitudes and values, educa-
tional practices, leisure activities, media exposure,
socio-economic and immigrant status, Gaelic-English
bilinguals do not differ from British English mono-
linguals. If bilingualism, rather than ethnic or cul-
tural background, is linked to superior executive
control, then both bilingual groups should exhibit
an advantage compared to the monolinguals.

A bilingual advantage in executive control may
also be attenuated or aggravated by factors oper-
ating within monolinguals, such as using different
dialectal varieties of a language. To date, little is
known about the cognitive demands imposed by
dialect use. Even though dialects are considered to
be mutually intelligible, they still require manage-
ment of competing phonetic and lexical variants.
Compared to the relatively moderate differences
between regional and social varieties of English in
the USA and Canada, the countries from which
the majority of monolingual controls have been
recruited so far, Britain has considerable dialectal
diversity: Speakers of British English are routinely
exposed to many distinct varieties of English (e.g.
Scots, Scouse, Geordie, etc.) in addition to the
standard variety. Specifically, in Scotland, 85% of
the population report using one of the local
varieties of the Scots dialect to varying degrees
(Scottish Government Social Research, 2010) in
addition to Standard Scottish English (SSE). Local
varieties of Scots differ considerably from SSE in
phonetic, lexical and even some syntactic features
(Smith & Durham, 2012). As a result, bidialectal
speakers must be able to: monitor continuously
who can or cannot be addressed in Scots, choose
appropriate articulatory settings and inhibit com-
peting phonetic and lexical variants of the lan-
guage variety not currently in use. If use of
multiple dialects incurs executive control benefits
similar to those observed in bilinguals, then
differences in executive control between bidialec-
tal monolinguals and bilinguals might be attenu-
ated. It is, therefore, important to control dialect
use in monolinguals. To this end, we tested three
monolingual control groups: (1) bidialectal speak-
ers who reported switching routinely between SSE
and Dundonian, a local variety of Scots spoken in

642 KIRK ET AL.

North-Eastern Central Scotland, (2) mono dialectal
speakers of SSE, the English variety spoken by
the Gaelic-English bilinguals, who resided in the
same locale as the bidialectals, but reported not
using Dundonian Scots despite having full com-
prehension of it and (3) monolingual speakers of
Anglo-English, the same variety spoken in the
South of England by the majority of the Asian
Language-English bilinguals, and to whom Scots
was unfamiliar and often unintelligible. We use the
label monodialectal to refer to those monolingual
participants who shared a geographical and cul-
tural background with the bidialectal participants;
however, it should be noted that these monolin-
guals also represent the most appropriate control
group for the Gaelic-English bilinguals.

METHOD

We examined inhibitory control using the Simon task
as employed in Experiment 1 of Bialystok et al.
(2004); the experiment that provided the very first
evidence for an inhibitory control advantage in older
bilinguals. The Simon task requires participants to
inhibit a pre-potent spatial cue when responding to
the colour of a stimulus. If an inhibitory control
advantage arises from routine use of two languages
but not dialects, regardless of ethnic and cultural
background, then both bilingual groups should dis-
play a smaller Simon effect compared to the bidia-
lectal, monodialectal and monolingual groups. If
regular use of dialect also results in an inhibitory
control advantage, then bidialectals too should exhibit
a smaller Simon effect compared to monodialectals
and monolinguals. Finally, if differences in cultural
and ethnic background associated with immigrant
status are related to an inhibitory control advantage,
then only the Asian Language-English bilingual
group should exhibit a smaller Simon effect. We
measured verbal intelligence to ensure equal English
proficiency between the groups, as well as non-verbal
intelligence and SES to rule out these alternative
sources for group differences in inhibitory control.

Participants

Eighty older adults (mean age = 70.8 years, SD =
7.5 years, range = 60.0-89.0 years) participated in
the experiment. Sixteen bilingual participants (six
men) were speakers of Gaelic and SSE. Sixteen
bilingual participants (10 men) were speakers
of English and either Bengali, Gujarati, Hindi,

Malay, Punjabi or Urdu who had immigrated to
the UK before 35 years of age. Sixteen bidialectal
participants (seven men) were speakers and regu-
lar users of both SSE and Dundonian Scots.
Sixteen monodialectal participants (five men) were
monolinguals speakers of SSE who had regular
exposure to and could comprehend (but did not use)
Dundonian Scots. Finally, 16 monolingual partici-
pants (six men) were speakers of Anglo-English
spoken in the South of England. The monodialectal
and bidialectal participants were recruited from
the Dundee area, the Gaelic-SSE bilinguals were
recruited from the Western Isles and the West coast
of Scotland, the English monolinguals were recruited
from different parts of England and Scotland (all but
one had not lived in Scotland for any considerable
length of time and were either visitors or had recently
retired to the area). The Asian language bilinguals
were recruited from London and Dundee, and their
age of arrival in the UK (M = 26.6 years, SD = 4.8
years, range = 14.0-35.0 years) was similar to the 21.5
years reported for the bilinguals in Salvatierra and
Rosselli (2010).

The Background Questionnaires (described
below) revealed that the bilinguals' daily use of
their non-English language(s) and the bidialectals'
use of Dundonian Scots ranged between 30% and
70% of time. The monodialectals reported less than
25% use of Dundonian Scots. In addition to the 80
participants included in the final analysis, a number
of other participants were tested but excluded for
various reasons: Three participants reported predo-
minantly using Dundonian Scots and, as it proved
impossible to recruit further monodialectal speakers
of this type, were excluded from the study. Nine
bilinguals reported percentages of English use out-
side the 30-70% range. Two participants were
excluded for having extremely low English profi-
ciency as measured in the Vocabulary subscale of
the WASI. Five participants were excluded for
having an age of arrival in the UK greater than 40.
Four participants failed to perform the Simon task
correctly, and data for one participant were not
recorded due to equipment malfunction.

Materials

Background Questionnaires. One background ques-
tionnaire inquired about the participants' educa-
tional background, the occupations they had held
throughout their working lives, as well as daily usage
of the different varieties of English and of other

NO REDUCED SIMON COST IN ELDERLY BILINGUALS

643

foreign languages; Scottish participants were also
asked about their use of varieties of Scots.

Bilinguals and bidialectals additionally received
modified versions of the Language Experience
and Proficiency Questionnaire (LEAP-Q; Marian,
Blumenfeld, & Kaushanskaya, 2007), a question-
naire designed to determine bilingual language
status through proficiency self-ratings that has
been validated using behavioural measures of
language proficiency. The LEAP-Q was adapted
for use with dialect speakers by asking to what
extent participants were fluent in one or two
varieties, e.g. SSE and Dundonian Scots, and the
age at which they became fluent.

Wechsler Abbreviated Scale of Intelligence
(WASI). Two subscales of the WASI were used
to determine participants' verbal and non-verbal
IQ. The Vocabulary subscale tested participants'
verbal reasoning ability and ability to give defini-
tions of words. The Matrix Reasoning subscale
contained visuo-spatial patterns designed to meas-
ure abstract non-verbal reasoning ability. Partici-
pants' raw scores were converted to ?-scores,
which are normalised for each age range.

Simon task. We used the same procedure as
Experiment 1 in Bialystok et al. (2004). Partici-
pants were presented with red and blue squares,
half of which appeared on the left side of the screen
and half on the right. Participants were asked to
press the "1" key on the left or the "0" key on the
right of the keyboard, depending on the colour of
the square. The keys were marked with white
stickers on the keyboard. In congruent trials, the
response key associated with the colour of the
square was located on the same side as the square.
In incongruent trials, the response key was located
on the opposite side requiring participants to
inhibit the spatial cue. The reaction time difference
between incongruent and congruent trials is con-
sidered to be a measure of inhibitory control.
Participants were given 4 congruent and 4 incon-
gruent practice trials with feedback before moving
on to the 28 critical trials (7 each of congruent red,
congruent blue, incongruent red and incongruent
blue) presented without feedback.

Procedure

Participants were first given the Background Ques-
tionnaire followed by the LEAP-Q, if appropriate,
before completing the Vocabulary and Matrix

Reasoning subscale of the WASI. Finally, the Simon
task was administered, with presentation controlled
by Eprime (Psychology Software Tools). Partici-
pants first saw a fixation cross in the middle of the
screen for 800 ms, followed by an interval of 250 ms.
Colour assignment to key location was counter-
balanced across participants. Then, a red or a blue
square appeared either to the left or the right of
the screen, subtending five degrees of visual angle.
The squares were visible for 1,000 ms if there was no
response. Timing began with the onset of the
stimulus and was terminated with the response.
The next item started after a 500 ms inter-stimulus
interval. The experiment began with eight practice
trials for which participants' received feedback,
followed by randomised presentation of 28 critical
trials presented without feedback.

RESULTS

Results for the linguistic, cognitive and demo-
graphic variables as well as the reaction times
(RTs) and error rates for the Simon task of the
five participant groups are given in Table 1.

Age

Although all participants were over the age of
60 years, it is important to check that there were
no age differences between the groups which was
confirmed by a one-way analysis of variance
(ANOVA), p = .62.

Percent language use

A one-way ANOVA comparing the self-reported
percentages of daily use of either Anglo-English or
SSE yielded a significant effect of group, F(4, 75) =
91.0, p < .001. Post-hoc tests using Tamhane's T2
for unequal variances indicated that, as expected,
both bilingual groups and the bidialectals reported
significantly less use of English (i.e. only an average
of 48% of time) than monolinguals and monodia-
lectals, all p's < .001.

Socio-economic status

We disregarded participant income as a measure of
SES as 75% of the participants were retired. Instead,
we used the 2010 Standard Occupation Classification
(UK Office of National Statistics) to categorise

644 KIRK ET AL.

TABLE 1

Means and standard deviations (in parentheses) for linguistic, demographic and cognitive measures

A/in n nil n cti i nlv

Bilinguals

Monolinguals

Mono-dialectals

Bidialectals

Gaelic- English

Asian-English

Age

69.5 (8.6)

69.7 (7.7)

72.4 (8.2)

69.8 (5.5)

72.6 (7.3)

WASI vocabulary

60.3 (9.6)

57.1 (8.4)

55.6 (6.7)

57.9 (9.0)

53.6 (14.2)

WASI matrix

61.0 (10.5)

59.5 (10.3)

59.1 (7.7)

59.5 (5.7)

56.2 (6.9)

Skill level* (1-4)

3.1 (1.2)

2.9 (0.9)

2.4 (0.9)

3.4 (0.8)

2.7 (1.1)

Percentage use of English**

100.0 (0.0)

94.6 (7.3)

52.6 (9.7)

44.3 (15.4)

52.8 (15.0)

Congruent RTs

608.3 (78.6)

576.1 (66.3)

614.9 (173.6)

594.2 (125.8)

714.1 (202.1)

Incongruent RTs

693.7 (125.5)

674.6 (97.6)

696.5 (190.4)

684.5 (157.1)

809 (207.71)

Percentage of error rates

1.8%

1.6%

2.5%

3.1%

4.2%

Simon cost

85.4 (85.4)

98.49 (66.5)

81.6 (51.7)

90.3 (104.0)

94.9 (55.0)

Significant differences between groups based on appropriate statistical test (explanations in text) with *p < .05 and **p < .001.

participants' occupations into one of four skill levels
based in the amount of formal qualifications or
work-based training estimated to be necessary to
perform each occupational task. These skill levels
ranged from 1 (occupations requiring general edu-
cation) to 4 (professional/managerial occupations
requiring degree-level education). A Kruskal-Wallis
test revealed a significant difference between groups,
H(4) = 9.62, p = .047, with mean ranks of 29.0, 36.4,
39.6, 46.5 and 51.0 for bidialectals, Asian Language-
English bilinguals, monodialectals, monolinguals and
Gaelic-English bilinguals, respectively. A post-hoc
test using a Bonferroni-corrected Mann-Whitney
test showed that the only significant difference was
that between bidialectals who had a significantly
lower skill level than Gaelic-English bilinguals,
U=51,p< .005.

WASI

WASI scores were missing for one monodialectal
participant who was unable to complete the
session. One-way ANOVAs comparing perform-
ance of the groups on the Vocabulary and Matrix
subscales separately yielded no significant effects,
all p's > .39.

Simon task

Participants committed a total of 2.7% of errors.
Error rates were submitted to a 5 (Group: bidia-
lectal, monodialectal, monolingual, Gaelic-SSE
bilingual, Asian Language-English bilingual,) x 2
(Trial Type: congruent, incongruent) ANOVA,
which yielded a significant effect of Trial Type:
F(l, 75) = 24.04, p < .001, with incongruent trials

yielding higher error rates than congruent trials, but
no significant interaction between Trial Type and
Language Group. For correct trials, reaction times
>2.5 SD above the mean were excluded from the
analysis, which affected an additional 57 (2.6%)
trials. For the RTs (see Figure 1), a similar 5x2
ANOVA yielded a main effect of Trial Type, F(l,
75) = 115.1, p < .001. The effect of Group fell short
of significance, F(4, 75) = 2.23, p = .074, reflecting a
trend towards slower RTs in the Asian Language-
English bilinguals. There was no significant inter-
action between Group and Trial Type. An analysis

□ congruent
■ incongruent

Language Crojp

Figure 1. Reaction times for congruent and incongruent trials in
the Simon task in bidialectals, monodialectals, monolinguals,
Gaelic-English bilinguals and Asian Language-English bilinguals.
Error bars show 1 SE.

NO REDUCED SIMON COST IN ELDERLY BILINGUALS

645

using median RTs yielded similar results showing a
main effect of Trial Type, F(l, 75) = 81.47, p < .001,
and an effect of Group which fell short of signific-
ance, F(4, 75) = 2.43, p = .055. Inspection of the
distribution of mean and median RTs across all
participants revealed one slow outlier in the Asian
Language-English bilingual group. Removal of this
participant from the reaction time analysis con-
firmed the effect of Trial Type, F(l, 74) = 112.97,
p < .001, and showed no other effects.

Because higher SES has been associated with
improved executive functioning (Morton & Harper,
2007), we conducted an additional ANOVA includ-
ing Skill Level instead of Group as between-subjects
factor. This analysis confirmed the slower reaction
time for incongruent trials as indicated by the main
effect of Trial Type, F(l, 76) = 98.1, p < .001, but did
not yield any other significant effects.

These results differ from the Bialystok et al.'s
(2004) study where older bilinguals exhibited
dramatically smaller Simon effects. One possible
explanation for this discrepancy may be related to
different treatment of reaction time outliers. Bia-
lystok et al. (2004) do not report any exclusion of
outliers. To achieve comparability with that study,
we repeated the ANOVA with all RTs from the
correct responses included. This analysis yielded a
main effect of Trial Type, F(l, 75) = 10.53, p < .01,
but no effect of Group and no interaction between
the two factors. In sum, as expected, all partici-
pants showed significantly slower RTs for incon-
gruent trials in the Simon task confirming that
inhibiting the incongruent spatial location of the
stimulus required additional inhibitory effort. Cru-
cially, the lack of an interaction suggests that there
is no evidence for group differences in the magni-
tude of the Simon effect, and thus, no evidence for
differences in inhibitory control between bilin-
guals, bidialectals and monolinguals.

However, since traditional null hypothesis sig-
nificance testing does not directly test acceptance
of the null hypothesis (see Kruschke, 2011), we
used a Bayesian approach to compare the likeli-
hood of a model assuming no differences in
inhibitory control between monolinguals and bilin-
guals with one assuming that there are differences
between monolinguals and bilinguals. To this end,
we grouped the three monolingual (n = 48) and
two bilingual (n = 32) groups together and
computed the Simon cost as the difference
between RTs for congruent and incongruent trials.
Using the Bayes Factor (BF) package in R (Morey
& Rouder, 2011) and a Cauchy prior (Rouder,
Speckman, Sun, Iverson, & Morey, 2009), we

obtained BF = 0.179 for the Simon Cost, BF = 0.622
for congruent RTs and BF = 0.541 for incongru-
ent RTs. As it can be argued that our bidialectal par-
ticipants know two varieties of a language, and
hence, it is unclear to what extent they resemble
monolinguals or bilinguals, we performed the same
analysis with the bidialectal group removed, and
obtained BF = 0.189 for the Simon cost, BF = 0.854
for congruent RTs and BF = 0.597 for incongruent
RTs. Both of these analyses provide evidence for
acceptance of the null hypothesis of no difference
between monolinguals and bilinguals in Simon cost
as the BFs were below 1 (Rouder et al, 2009).

DISCUSSION

Our findings did not show an advantage in non-
linguistic inhibitory control for older Gaelic-
English and Asian Language-English bilinguals,
nor did we find such an advantage for bidialectal
speakers who routinely use both Dundonian Scots
and SSE. Moreover, there was no global reaction
time advantage for bilinguals and bidialectals,
suggesting that the groups did not differ in general
executive processing related to conflict monitoring
either (Hilchey & Klein, 2011). If anything, one
bilingual group, the Asian Language -English
bilinguals showed a trend towards slower RTs, a
finding that goes in the opposite direction from
what a bilingual advantage would predict.

Our experiment was closely modelled after
Experiment 1 in Bialystok et al. (2004). For the
monolinguals, that experiment showed mean RTs
of 1,437 ms for the congruent trials and 3,150 ms
for the incongruent trials. For the bilinguals, the
RTs were somewhat faster (congruent: 911 ms,
incongruent: 1,959 ms). These are unusually slow
overall RTs, in stark contrast to the much faster
RTs in our study, which followed the same timing,
contained the same number of trials and had a
comparable sample size. The magnitude of the
Simon effect in Experiment 1 of Bialystok et al.
(2004) is also far beyond what is considered to be
typical in older adults (Hilchey & Klein, 2011; Van
der Lubbe & Verleger, 2002), leaving open the
possibility that group differences between older
bilinguals and monolinguals emerge only for un-
usually long RTs which may be indicative of a
substantial slowing of cognitive performance in
some older populations, perhaps due to dimin-
ished experience with computerised testing or due
to sub-clinical effects of dementia. However, the
fact that subsequent studies (Bialystok et al, 2008;

646 KIRK ET AL.

Salvatierra & Rosselli, 2010; Schroeder & Marian,
2012) with larger numbers of trials found a
bilingual advantage using the Simon task for older
bilinguals displaying overall RTs similar to the
ones reported here suggests that the bilingual
advantage in Bialystok et al. (2004) is not just an
artefact of unusually long RTs.

What then can account for our failure to
replicate the findings of Experiment 1 in Bialystok
et al. (2004)? We can rule out differences in age
and experimental protocol, and we established
that differences in SES, cultural and ethnic back-
ground as well as immigrant status did not affect
the results either. Moreover, typological distance
between the languages was large in both studies
making this also an unlikely source for the incon-
sistent results. Potentially, however, there remain
qualitative differences in the way in which bilin-
guals used their two languages throughout their
lives as different interactional contexts can impose
different demands on executive control processes
(Green & Abutalebi, 2013). Compared to dual
language use (i.e. use of both languages with
different interlocutors in the same setting) dense
code-switching and single -language use (i.e. use of
both languages in different, non-overlapping set-
tings such as home vs. work) reduce the need for
selective response inhibition of the type assessed
by the Simon task. Unfortunately, purely quantit-
ative estimates of language use provided in most
studies, including ours, make it difficult to identify
the habitually encountered interactional contexts
for each bilingual. Still, to reconcile the different
results, it may be helpful to consider language of
schooling as a proxy for habitually encountered
interactional context: Schooling in only one lan-
guage should promote single -language use if the
language of schooling is preferred for a wide range
of interactional settings and topics, whereas the
other language is reserved for a restricted range of
settings and topics. Relatedly, if reading is prac-
ticed predominantly in one language, it will lead to
considerable gains in vocabulary size compared
to the other language so that labels for many
concepts may be known only in the language
preferred for literacy. In such a scenario, lexical
competitors from the other language may not be
activated for many semantic domains and, hence,
are less likely to interfere.

As indicated above, the Gaelic-English bilinguals
received no Gaelic-medium schooling during their
primary and secondary education, which likely
promoted compartmentalised single -language use
in many settings, even if overall amount of use was

balanced. Similarly, most of the Asian Language-
English bilinguals immigrated to the UK after
having completed their education in their first
language, making frequent single -language use
also a likely scenario. In contrast, the bilinguals
in Bialystok et al. (2004) were educated in both
languages allowing for the possibility of more
frequent dual-language use. This idea also echoes
with the findings from Gaelic-English bilingual
children who attended Gaelic-medium schools
and showed benefits in verbal and non-verbal
IQ compared to Sardinian-Italian bilingual chil-
dren who received no schooling in Sardinian
(Lauchlan, Parisi, & Fadda, 2013). Even though
measures of general cognitive ability are different
from measures of inhibitory control, this finding
may leave open the possibility that schooling in
both languages promotes habitual dual-language
use and shapes the associated demands on exec-
utive control accordingly, which may eventually
lead to a bilingual advantage. However, studies on
non-immigrant Spanish-Basque bilingual children
schooled in both languages showed no cognitive
control advantages compared to Spanish monolin-
guals carefully matched on a variety of variables
(Anton et al, 2014; Dunabeitia et al., 2013),
although it should be noted that the bilingual
children were exposed to Spanish somewhat more
frequently. Similarly, Welsh-English bilingual chil-
dren and adults showed no advantage in cognitive
control and meta-linguistic awareness compared to
matched English monolinguals regardless of pat-
terns of language dominance and use in the home
(Gathercole et al., 2014), although it remains unclear
to what extent the bilingual children were schooled
in Welsh. These group differences underscore the
importance to carefully match the various circum-
stances that may influence interactional contexts
across bilingual populations.

In sum, our failure to observe superior inhibitory
control in older Gaelic-English bilinguals, Asian
Language-English bilinguals and Dundonian-SSE
bidialectals suggests that neither differences in
cultural and ethnic background related to immigrant
status of the bilinguals, nor routine use of dialect
varieties in the monolinguals seem to account for
the inconsistencies in findings. Although an analysis
of other age groups is beyond the scope of this
paper, it is worth mentioning that such inconsisten-
cies in terms of finding a bilingual advantage also
exist in studies of inhibitory control using the Simon
task in children, in younger and in middle-aged
adults, as well as other executive processing tasks
(e.g. Stroop task, Flanker task, anti-saccade task)

NO REDUCED SIMON COST IN ELDERLY BILINGUALS

647

and for other executive processing components (e.g.
response suppression, switching, monitoring and
updating — for an overview over studies that do not
replicate a bilingual advantage see Paap & Green-
berg, 2013). To reconcile these inconsistencies,
future research needs to describe the specific beha-
vioural ecology of bilingual language use in more
detail and develop instruments to establish the
recurrent, habitually encountered interactional con-
texts with the aim of exploring how these contexts
shape cognitive control demands and whether they
provide the necessary extended practice of inhibi-
tion and executive control that may transfer to non-
linguistic domains.

Original manuscript received March 2014
Revised manuscript received May 2014
Revised manuscript accepted May 2014
First published online June 2014

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